Role of MeCP2 as a Chromatin Architectural Protein

MeCP2 作为染色质结构蛋白的作用

• 批准号: 6867379
• 负责人: CHRISTOPHER L. WOODCOCK
• 金额: $ 24.67万
• 依托单位: UNIVERSITY OF MASSACHUSETTS AMHERST
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6867379
• 关键词: Rett syndrome; amidohydrolases; binding sites; chromatin; conformation; crosslink; disease /disorder etiology; electron microscopy; gene induction /repression; gene interaction; gene mutation; genetic regulation; nucleoproteins; nucleosomes; pathologic process; protein binding; protein structure function; western blottings

DESCRIPTION (provided by applicant): Preliminary work has produced a surprising, and potentially important finding for understanding the etiology of Rett Syndrome. The new data show that simply by binding to chromatin, MeCP2 induces a dramatic change in 3D conformation, resulting in a marked increase in compaction. Unlike the chromatin compaction induced by histone H1, which is highly dependent on salt concentration and produces a zig-zag conformation, MeCP2 compaction is independent of salt concentration, and proceeds through edge-to-edge contact between nucleosomes. Further, this MeCP2-induced compaction appears not to require DNA methylation. Work by others has clearly demonstrated that the gene silencing function of MeCP2 can occur by the recruitment of histone deacetylase (HDAC) complexes, followed by hypoacetylation of core histones leading to the generation of local areas of heterochromatin. The new findings suggest a dual mechanism of heterochromatin formation by MeCP2 - one component being an intrinsic consequence of MeCP2 binding to chromatin, the other via HDAC recruitment. This proposal is aimed at understanding the molecular mechanism(s) by which MeCP2 compacts chromatin, and the impact on this mechanism of MeCP2 mutants known to be important in RTT. A primary technique to be used in the proposed research is direct imaging by electron microscopy (EM), complemented by appropriate biochemical and biophysical tools. EM has the advantage over 'bulk' techniques that the 3D conformation of chromatin is accessible, allowing the locations and orientations of nucleosomes in individual chromatin arrays to be found. Specific aims include: determining which domain(s) of MeCP2 contribute to its ability to compact chromatin; determining the relative contributions of nucleosomal and linker DNA in MeCP2 binding; and, in view of the report that MeCP2 can displace histone H1 from chromatin, determining whether H1 and MeCP2 share the same or overlapping binding sites on chromatin. The results will provide fundamental new information of the interactions of MeCP2 with chromatin, information that can be drawn on as potential therapies for RTT are formulated and evaluated.

描述（由申请人提供）：初步工作为理解RETT综合征的病因而产生了令人惊讶的且潜在的重要发现。新数据表明，仅通过与染色质结合，MECP2诱导了3D构象的急剧变化，从而导致压实显着增加。与由组蛋白H1诱导的染色质压实（高度取决于盐浓度并产生锯齿形构象）不同，MECP2压实与盐浓度无关，并且通过核小体之间的边缘到边缘接触进行。此外，这种MECP2诱导的压实似乎不需要DNA甲基化。 其他人的工作清楚地表明，MECP2的基因沉默功能可以通过募集组蛋白脱乙酰基酶（HDAC）络合物来实现，然后核心组蛋白的脱乙酰化导致异染色质的局部区域产生。新发现表明，MECP2形成异染色质的双重机制 - 一种成分是MECP2与染色质结合的固有结果，另一种是通过HDAC募集。 该建议旨在理解MECP2压缩染色质的分子机制，以及对这种已知在RTT中很重要的MECP2突变体的影响。拟议研究中要使用的主要技术是通过电子显微镜（EM）进行直接成像，并以适当的生化和生物物理工具进行补充。 EM比“大量”技术具有优势，即可以访问染色质的3D构象，从而可以找到单个染色质阵列中核小体的位置和方向。 具体目的包括：确定哪些MECP2域有助于其紧凑型染色质的能力；确定MECP2结合中核小体和接头DNA的相对贡献；并且，鉴于MECP2可以从染色质中取代组蛋白H1的报告，确定H1和MECP2在染色质上是否共享相同或重叠的结合位点。 结果将提供MECP2与染色质的相互作用的基本新信息，可以制定和评估作为RTT潜在疗法的信息。